Successful early dietary intervention avoids obesity in patients with Prader-Willi syndrome: a ten-year follow-up

Infantile Hypothalamic Hamartoma: A Rare Presentation of Isolated Obesity

Hypothalamic hamartomas (HHs) are rare, benign brain tumors or lesions of the hypothalamus that are predominantly identified in cases of epilepsy and central precocious puberty (CPP), whereas isolated manifestations of infantile obesity are atypical. We herein report an 8-month-old boy with severe obesity (Kaup index 26.4 [>100th percentile]) and uncontrollable hyperphagia. His growth chart demonstrated remarkable weight gain that exceeded the length gain in magnitude. Brain magnetic resonance imaging identified a lesion consistent with HH. There were no episodes or clinical findings of epilepsy, CPP, or Cushing disease. Hypothalamic obesity should be considered in the diagnosis even in infants with excessive weight gain due to overeating.

Prader-Willi Syndrome in Adults: An Update On Nutritional Treatment and Pharmacological Approach

PURPOSE OF REVIEW

Prader-Willi syndrome (PWS) is a rare and complex genetic disorder with multiple effects on the metabolic, endocrine, and neurological systems, as well as behavioral and intellectual difficulties. Despite advances in understanding the genetic basis of obesity in PWS, there are conflicting data on its management. Therefore, the present manuscript aims to provide an update on the nutritional treatment and pharmacological approach in adult patients with PWS.

RECENT FINDINGS

The management of obesity in patients with PWS is challenging and requires the cooperation of an experienced multidisciplinary team, including the nutritionist. An adequate clinical evaluation including nutritional and biochemical parameters should be performed to tailor the best therapeutic strategy. Both lifestyle and pharmacological interventions may represent useful strategies to prevent the high rate of morbidity and mortality related to PWS. The use of bariatric surgery is still controversial. Although it is imperative to adopt an obesity prevention strategy in childhood, there is promising evidence for the treatment of obesity in adulthood with current obesity medications in conjunction with lifestyle interventions.

Prader-Willi syndrome: an update on obesity and endocrine problems

Prader-Willi syndrome (PWS) is a rare complex genetic disorder that results from a lack of expression of the paternally inherited chromosome 15q11-q13. PWS is characterized by hypotonia and feeding difficulty in early infancy and development of morbid obesity aggravated by uncontrolled hyperphagia after childhood and adolescent. Dysmorphic facial features, delayed motor and language development, various degrees of cognitive impairment, and behavioral problems are common in PWS. Without early, intensive nutritional therapy along with behavioral modification, PWS patients develop severe obesity associated with type 2 diabetes, obstructive sleep apnea, right-side heart failure, and other obesity-related metabolic complications. Hypothalamic dysfunction in PWS can lead to several endocrine disorders, including short stature with growth hormone deficiency, hypothyroidism, central adrenal insufficiency, and hypogonadism. In this review, we discuss the natural history of PWS and the mechanisms of hyperphagia and obesity. We also provide an update on obesity treatments and recommendations for screening and monitoring of various endocrine problems that can occur in PWS.

Improved Motor Proficiency and Quality of Life in Youth With Prader-Willi Syndrome and Obesity 6 Months After Completing a Parent-Led, Game-Based Intervention

PURPOSE

To determine changes and potential differences in physical activity (PA), gross motor proficiency (MP), and health parameters after a 6-month follow-up (FU) period following participation in a parent-led PA intervention in youth with or without Prader-Willi syndrome (PWS).

METHODS

About 42 youth with PWS and 65 youth without PWS but with obesity (body fat percentage >95th percentile for age and sex), aged 8-16 years, participated. The intervention included preplanned PA sessions containing playground and console-based video games scheduled 4 days per week for 24 weeks. Families received training and curriculum materials. PA (accelerometry), MP (Bruininks-Oseretsky Test of MP), and health-related quality of life were obtained before (PRE), after completing the intervention (POST), and at FU.

RESULTS

There were no significant changes in PA at any time point. At FU and POST, participants showed higher bilateral coordination (PRE = 9.3 [0.4], POST = 11.7 [0.5], and FU = 11.1 [0.6]); speed and agility (PRE = 9.2 [0.4], POST = 10.8 [0.4], and FU = 11.5 [0.5]); and strength (PRE = 8.0 [0.3], POST = 9.2 [0.3], and FU = 9.2 [0.3]) than at PRE. At FU (80.3 [2.1]) and POST (79.8 [1.7]), youth without PWS showed higher health-related quality of life than PRE (75.0 [1.8]).

CONCLUSION

The improvements in MP and health-related quality of life at FU suggest long-term durability of intervention outcomes.

Dietary intake and growth in children with Prader-Willi syndrome

BACKGROUND

The management of Prader-Willi Syndrome (PWS) requires strict dietary supervision to prevent obesity, avoid micronutrient deficiencies and ensure optimal growth. The present study aimed to examine the growth and dietary intake of children with PWS.

METHODS

All children with genetically confirmed PWS attending Children's Health Ireland (CHI) at Tallaght (n = 44) were invited to participate. Anthropometry was performed and body composition measured using bioelectrical impedance analysis. Three-day food diaries were used to evaluate dietary intake and the presence of early feeding issues was assessed. Serum haemoglobin, ferritin and vitamin D levels were measured.

RESULTS

Nineteen children participated, with a mean (range) age of 7.6 (0.6-18.1) years. Most were female (n = 14, 74%). Twenty-percent (n = 3) were underweight, 60% (n = 9) were healthy weight, n = 1 was overweight and n = 2 were obese. Mean (range) percentage body fat was 25.7% (10%-40%). Eigthy-three percent reported early feeding issues. Ninety-four percent (n = 16) achieved ≤ 100% of estimated average requirement (EAR) for energy. Mean daily energy intake for ≤ 5 years old was 722 kcal (9 kcal cm^-1 /72-112% EAR); for those ≥ 12 years, it was 1203 kcal (8.3 kcal cm^-1 /41%-82% EAR). Suboptimal calcium, vitamin D, iron, zinc and fibre intake was evident. Iron deficiency anaemia and vitamin D insufficiency occurred in two children.

CONCLUSIONS

The present study provides the first Irish data for PWS and shows that energy intake does not appear to be excessive, with four in five patients being underweight or of a normal BMI. Suboptimal dietary intake of several micronutrients was evident and biochemical nutrient deficiencies were present.

Central hypothyroidism improves with age in very young children with Prader-Willi syndrome

OBJECTIVE

Abnormalities in the hypothalamic-pituitary-thyroid (HPT) axis have been implicated in Prader-Willi syndrome (PWS); however, limited information is currently available on age-dependent alterations in the HPT axis. We herein investigated age-dependent differences in thyroid hormone levels in PWS children.

DESIGN/PATIENTS/MEASUREMENTS

Free T4 (FT4), free T3 (FT3) and thyroid-stimulating hormone (TSH) concentrations were retrospectively compared between genetically confirmed PWS children (N = 43, median age: 11.2 months) and controls (N = 85, median age: 14.5 months) matched for age, sex, body weight-SD score (SDS), height-SDS, body mass index-SDS and serum albumin level, a marker of the nutritional status. Subjects were subdivided into two groups based on their age: an infant group aged between 1 and 11 months (PWS: N = 22, controls: N = 30) and a toddler group aged between 12 and 47 months (PWS: N = 21, controls: N = 55). None of the subjects had ever been treated with growth hormone or levothyroxine.

RESULTS

After adjustments for confounding variables, in the infant group, FT4 levels (pmol/L) were significantly lower in PWS (11.24 in PWS vs 14.32 in controls, P = .0002), whereas no significant differences were observed in FT3 or TSH levels. In the toddler group, no significant differences were noted in FT4 (12.23 in PWS vs 15.31 in controls, P = .10), FT3 or TSH levels. The FT3/FT4 ratio was significantly increased in PWS in both groups. FT4 levels were positively correlated with age in PWS.

CONCLUSIONS

Infants with PWS had lower FT4 levels, but FT3 levels were normal, indicating that the levothyroxine replacement therapy may not need to be routinely performed.

Anti-obesity effects of α-amylase inhibitor enriched-extract from white common beans (Phaseolus vulgaris L.) associated with the modulation of gut microbiota composition in high-fat diet-induced obese rats

α-Amylase inhibitors (α-AI) have great potential to treat obesity. In this study, an α-AI enriched extract (α-AIE) with a specific activity of 1027.1 ± 154.2 (U per mg protein) was prepared from white common bean (Phaseolus vulgaris L.) seeds. Its anti-obesity effect and gut microbiota modulation properties were verified in high-fat diet-induced obese rats. The intake of the α-AIE significantly reduced body weight gain and improved serum lipid levels (p < 0.05). In addition, rats fed the α-AIE diet exhibited higher total short-chain fatty-acid (SCFA) concentrations (p < 0.05) in their colonic contents. β-Diversity analysis, principal component analysis and a Venn diagram showed that α-AIE administration changed the gut microbiota composition. At the phylum level, the relative abundances of Firmicutes and Proteobacteria decreased and the relative abundances of Bacteroidetes and Akkermansia increased. In addition, 89 operational taxonomic units (OTUs) significantly responding to the high-fat diet and 30 OTUs significantly responding to the α-AIE were identified. The OTUs enriched by the α-AIE were mainly assigned to putative SCFA-producing bacteria, including Bacteroides, Butyricoccus, Blautia and Eubacterium. Twenty-two OTUs were found to be significantly correlated with obesity indexes. Taken together, the present results suggest that the intake of the α-AIE attenuated obesity and modulated gut microbiota.

Visceral adipose tissue resides within the reference range in children with Prader-Willi syndrome receiving nutritional intervention on a regular basis

Nutritional intervention for maintaining an appropriate body composition is central to the management of Prader-Willi syndrome (PWS). Despite evidence that visceral adipose tissue (VAT) is associated with increased metabolic risks, the effects of nutritional intervention on fat distribution have not been evaluated for PWS children. We herein investigated fat distribution in 20 genetically diagnosed PWS children (9 males and 11 females); 17 of which received nutritional intervention with or without growth hormone (GH) treatment [GH-treated group (n = 8), GH-untreated group (n = 9)]. GH treatment continued for median of 4.9 years. GH treatment significantly increased height standard deviation score (SDS) whereas body weight SDS and body mass index SDS were not affected in GH-treated group. In GH-untreated group, height SDS significantly decreased during approximately 5 years of follow-up. Fat distribution was evaluated at the median age of 6.93 years in GH-treated group and 7.01 years in GH-untreated group. VAT was maintained within the reference range in both groups. Subcutaneous adipose tissue (SAT) was elevated in GH-untreated groups compared to reference values whereas it was not in GH-treated group. The remaining three subjects, who had never received nutritional intervention or GH treatment, showed increased VAT and SAT. In conclusion, nutritional intervention is beneficial in maintaining VAT within the reference range during childhood, although excessive nutritional intervention may cause unfavorable effect on linear growth.

Specific Dietary Components and Gut Microbiota Composition are Associated with Obesity in Children and Adolescents with Prader-Willi Syndrome

Prader–Willi syndrome is a rare genetic disorder associated with impaired body composition, hyperphagia, and excessive weight gain. Strict dietary restrictions from an early age is crucial to prevent or delay the early onset of obesity, which is the main driver of comorbidities in these patients. The aim of this study was to identify dietary and gut microbiota components closely linked to weight status of these patients. We studied a cohort of children and adolescents with genetic diagnosis of Prader–Willi syndrome (N = 31), in which we determined adiposity by Dual-energy X-ray absorptiometry (DXA) and dietary composition with 4-day food records. Furthermore, we obtained fecal samples to assess microbiota composition by 16S sequencing. Multivariate regression models showed that body mass index standard deviation score (BMI-SDS) and body fat mass were directly associated with saturated fat intake and meat consumption, and inversely associated with fruit consumption. Furthermore, the gut microbiome from normal weight patients was characterized by higher phylogenetic diversity compared to those overweight or obese, with differential abundance of several genera, including Alistipes, Klebsiella, and Murimonas. Notably, Alistipes abundance was inversely correlated to adiposity, lipid and glucose homeostasis parameters, and meat intake. Our results suggest that limiting meat and increasing fruit intake might be beneficial for body weight management in children and adolescents with Prader–Willi syndrome.

A multidisciplinary approach to the clinical management of Prader-Willi syndrome

Background

Prader–Willi syndrome (PWS) is a complex neuroendocrine disorder affecting approximately 1/15,000–1/30,000 people. Unmet medical needs of individuals with PWS make it a rare disease that models the importance of multidisciplinary approaches to care with collaboration between academic centers, medical homes, industry, and parent organizations. Multidisciplinary clinics support comprehensive, patient‐centered care for individuals with complex genetic disorders and their families. Value comes from improved communication and focuses on quality family‐centered care.

Methods

Interviews with medical professionals, scientists, managed care experts, parents, and individuals with PWS were conducted from July 1 to December 1, 2016. Review of the literature was used to provide support.

Results

Data are presented based on consensus from these interviews by specialty focusing on unique aspects of care, research, and management. We have also defined the Center of Excellence beyond the multidisciplinary clinic.

Conclusion

Establishment of clinics motivates collaboration to provide evidence‐based new standards of care, increases the knowledge base including through randomized controlled trials, and offers an additional resource for the community. They have a role in global telemedicine, including to rural areas with few resources, and create opportunities for clinical work to inform basic and translational research. As a care team, we are currently charged with understanding the molecular basis of PWS beyond the known genetic cause; developing appropriate clinical outcome measures and biomarkers; bringing new therapies to change the natural history of disease; improving daily patient struggles, access to care, and caregiver burden; and decreasing healthcare load. Based on experience to date with a PWS multidisciplinary clinic, we propose a design for this approach and emphasize the development of “Centers of Excellence.” We highlight the dearth of evidence for management approaches creating huge gaps in care practices as a means to illustrate the importance of the collaborative environment and translational approaches.

Dietary intake in youth with prader-willi syndrome

Dietary management is important to prevent severe obesity in individuals with Prader-Willi syndrome (PWS); however, few studies have examined dietary intake and quality in youth with PWS. Our objective was to estimate intake of essential nutrients and diet quality in youth with PWS compared to those without PWS. Three-day food records were used to estimate intake of energy, nutrients, nutrient-density, foods, and adherence to healthy eating guidelines. Data were presented as medians and interquartile ranges with Mann-Whitney U and Fisher's test used to compare between groups with p < .05 considered significant. Youth with (n = 23) and without (n = 23) PWS were similar in age and sex distribution. The PWS group had a lower energy intake (p ≤ .001), higher nutrient density (p = .003), and better adherence to guidelines (p = .007) compared to the control group. The proportion with nutrient intake from food below Estimated Average Requirement or Adequate Intake were similar between groups. Fiber, vitamin D, calcium, and potassium intake were below recommendations in 50% or more in both groups. The inclusion of supplement intake lowered the proportion below recommendations, except for fiber and potassium. Youth with PWS had a similar nutrient intake as those without PWS despite a lower energy intake, which could be attributed to higher diet quality. However, more than half of youth with PWS were at risk of inadequate fiber, vitamin D, calcium, and potassium intake. A greater emphasis on nutrient-dense foods would improve nutrient intake, but supplements may be warranted in youth with PWS who do not meet recommendations.

The associations between diet and physical activity with body composition and walking a timed distance in adults with Prader-Willi syndrome

Background

Research on aging in Prader–Willi syndrome (PWS) is limited, although people with PWS are living longer. Individuals with PWS present with high fat mass, low lean mass, and low levels of physical activity (PA). Previous reports in children and young adults with PWS show inadequate nutrient intake and body fat percentage indicating obesity. Previous studies in PWS rarely included individuals beyond young adulthood, especially studies conducted in the United States. This study includes adults from 18 to 62 years of age, and includes 19 of the estimated 60 adult individuals with PWS in Oklahoma. Because individuals with PWS are living longer, information must be provided on aging with PWS. This study is a report of the initial data for a planned longitudinal study on aging with PWS.

Objective

Determine associations between body composition, diet, PA, and a timed walk for adults with PWS, and to assess adequacy of dietary intake for those individuals aging with PWS.

Design

This cross-sectional investigation determined dietary habits, PA, and body composition of adults with PWS, and tested associations between these variables.

Results

Participants ranged in age from 18 to 62 years. They had healthier body composition, at 26.8% body fat, than previously reported. Mean body mass index (BMI) was in the overweight range at 26.7. Those who consumed higher amounts of fat (as a percent of total kilocalories) had statistically significant lower body fat percentage, but this may simply reflect that individuals with lower body fat percentages felt freer to consume fat. Mean steps taken per day was 7631.7 steps but only 16% of participants met healthy PA recommendations despite participating in daily structured exercise. All participants’ diets met Dietary Guidelines for macronutrient distribution, but 80% were deficient in calcium, 100% were deficient in dietary vitamin D, and 87% were deficient in fiber. Sample size was small, so it was difficult to reach statistical significance, despite seeing clinical significance.

Conclusions

Recommend working toward healthy PA recommendations for all age groups by decreasing time in sedentary activity. Recommend increasing vitamin A and D fortified dairy products and high-fiber foods, and consider dietary supplementation, especially for calcium, vitamin D, and fiber.

Review of Prader-Willi syndrome: the endocrine approach

Prader-Willi syndrome (PWS) is a complex genetic disorder with implications on the endocrine and neurologic systems, metabolism, and behavior. Early in life, PWS is characterized by hypotonia and failure to thrive, followed by obesity and hyperphagia. Patients with PWS develop hypothalamic dysfunction which may lead growth hormone deficiency (GHD), hypogonadism, hypothyroidism, adrenal insufficiency, and poor bone mineral density (BMD). In addition to hypothalamic dysfunction, individuals with PWS have increased risk for obesity which may be complicated by metabolic syndrome and type 2 diabetes mellitus (T2DM). In this paper, we will review the current literature pertaining to the endocrine concerns of PWS and current recommendations for screening and management of these conditions.

Nutritional intervention with hypocaloric diet for weight control in children and adolescents with Prader-Willi Syndrome

Prader-Willi Syndrome (PWS) is a genetic disorder caused by the lack of expression of paternal alleles in the proximal region of the long arm of chromosome 15. Low inhibitory control and hyperphagia are two of the most severe neurobehavioral symptoms of the syndrome. The aim of the present study was to assess the efficiency of nutritional training program with the use hypocaloric diet for weight control in a group of five children and adolescents with PWS. The intervention program consisted of 10 sessions for parents' orientation during 8months. Patients had their anthropometric measures assessed (weight, height and body mass index - BMI). The main results indicate weight maintenance, height increase, and BMI decrease after intervention. These results were considered indicators of the program's efficiency.

Nutritional intakes in children with Prader-Willi syndrome and non-congenital obesity

BACKGROUND

Individuals with Prader-Willi syndrome (PWS) have extremely regulated diets to prevent the development of morbid obesity.

OBJECTIVE

This study evaluated potential deficiencies in macro and micronutrients in a cohort of youth with PWS and compared them to a group of children with non-congenital obesity and to US national recommendations.

DESIGN

Participants were 32 youth with PWS (age=10.8±2.6 years, body fat=46.7±10.1%) and 48 children without PWS but classified as obese (age=9.7±1.2 years, body fat=43.4±5.7%). Participants' parents completed a training session on food recording before completing a 3-day food record during a typical week including a weekend day and two weekdays, as well as a screening form indicating nutritional supplements use.

RESULTS

Youth with PWS reported less calories (1,312±75 vs. 1,531±61 kcal, p=0.03), carbohydrate (175±10 vs. 203±8 g), and sugars (67±5 vs. 81±4 g; p=0.04 for both) than obese. Youth with PWS consumed more vegetables (1.1±0.1 vs. 0.6±0.1 cups) and more of them met the daily recommendation (p<0.01 for both). Likewise, youth with PWS consumed more calcium than obese (899±53 vs. 752±43 mg) and more of them met the recommended daily dose (p=0.04 for both). The majority of participants in this study did not meet the vitamin D recommendation.

CONCLUSION

Despite consuming less calories, youth with PWS had a similar proportion of macronutrients in their diet as children with obesity. Micronutrient deficiencies in calcium and vitamin D in youth with PWS were noted despite a third of youth with PWS consuming multivitamin supplements. Special attention must be paid to the diets of youth with PWS and with obesity to ensure they are meeting micronutrient needs during this period of growth and development.

Individuals with Smith-Magenis syndrome display profound neurodevelopmental behavioral deficiencies and exhibit food-related behaviors equivalent to Prader-Willi syndrome

Smith-Magenis syndrome (SMS) is a neurodevelopmental disorder associated with intellectual disability, sleep disturbances, early onset obesity and vast behavioral deficits. We used the Behavior Problems Inventory-01 to categorize the frequency and severity of behavioral abnormalities in a SMS cohort relative to individuals with intellectual disability of heterogeneous etiology. Self-injurious, stereotyped, and aggressive/destructive behavioral scores indicated that both frequency and severity were significantly higher among individuals with SMS relative to those with intellectual disability. Next, we categorized food behaviors in our SMS cohort across age using the Food Related Problems Questionnaire (FRPQ) and found that problems began to occur in SMS children as early as 5-11 years old, but children 12-18 years old and adults manifested the most severe problems. Furthermore, we evaluated the similarities of SMS adult food-related behaviors to those with intellectual disability and found that SMS adults had more severe behavioral problems. Many neurodevelopmental disorders exhibit syndromic obesity including SMS. Prader-Willi syndrome (PWS) is the most frequent neurodevelopmental disorder with syndromic obesity and has a well-established management and treatment plan. Using the FRPQ we found that SMS adults had similar scores relative to PWS adults. Both syndromes manifest weight gain early in development, and the FRPQ scores highlight specific areas in which behavioral similarities exist, including preoccupation with food, impaired satiety, and negative behavioral responses. SMS food-related behavior treatment paradigms are not as refined as PWS, suggesting that current PWS treatments for prevention of obesity may be beneficial for individuals with SMS.

Prader-Willi, Angelman, and 15q11-q13 Duplication Syndromes

Three distinct neurodevelopmental disorders arise primarily from deletions or duplications that occur at the 15q11-q13 locus: Prader-Willi syndrome, Angelman syndrome, and 15q11-q13 duplication syndrome. Each of these disorders results from the loss of function or overexpression of at least 1 imprinted gene. This article discusses the clinical background, genetic cause, diagnostic strategy, and management of each of these 3 disorders.

Long-term echocardiographic and cardioscintigraphic effects of growth hormone treatment in adults with Prader-Willi syndrome

CONTEXT

In Prader-Willi syndrome (PWS), an altered GH secretion has been related to reduced cardiac mass and systolic function compared to controls.

OBJECTIVE

The objective was to evaluate the cardiovascular response to a 4-year GH therapy in adult PWS patients.

STUDY PARTICIPANTS

Study participants were nine severely obese PWS adults (three females, six males) and 13 age-, gender-, and body mass index-matched obese controls.

METHODS

In an open-label prospective study, assessment of endocrine parameters and metabolic outcome, whole-body and abdominal fat scans, echocardiography, and radionuclide angiography in unstimulated and dobutamine-stimulated conditions were conducted at baseline and after 1 and 4 years of GH treatment.

RESULTS

GH treatment increased IGF-1 (P < .0001), decreased C-reactive protein levels (P < .05), improved visceral fat mass (P < .05), and achieved near-significant changes of fat and fat-free body mass in PWS patients. Left ventricle mass indexed by fat mass increased significantly after 1 and 4 years of GH therapy (P < .05) without evident abnormalities of diastolic function, while a trend toward a reduction of the ejection fraction was documented by echocardiography (P = .054). Radionuclide angiography revealed stable values throughout the study of both the left and right ventricle ejection fractions, although this was accompanied by a statistically nonsignificant reduction of the left ventricle filling rate. A positive association between lean body mass and left ventricle ejection fraction was evident during the study (P < .05).

CONCLUSIONS

GH therapy increased the cardiac mass of PWS adults without causing overt abnormalities of systolic and diastolic function. Although the association between lean mass and left ventricle ejection fraction during GH therapy corroborates a favorable systemic outcome of long-term GH treatment in adults with PWS, subtle longitudinal modifications of functional parameters advocate appropriate cardiac monitoring in the long-term therapeutic strategy for PWS.

A population-based profile of 160 Australians with Prader-Willi syndrome: trends in diagnosis, birth prevalence and birth characteristics

Perceived temporal trends in recognition and diagnosis of Prader-Willi syndrome served as the rationale for an updated epidemiological profile of individuals with this syndrome. Data from the Victorian Prader-Willi Syndrome Register were used to explore birth prevalence, birth characteristics, timing of diagnosis, and molecular mechanism, and to identify trends over time. Maternal age, birth gestation, small for gestational age, and sex were compared across molecular mechanisms. Between 1951 and 2012 there were 160 individuals with Prader-Willi syndrome, known to the Victorian Prader-Willi Syndrome Register, who were born in the Australian state of Victoria. The birth prevalence for individuals with a molecular diagnosis of Prader-Willi syndrome was estimated to be 1:15,830 for 2003-2012. Compared to 1973-1981, the decade 2003-2012 saw an increase in the rate of molecular diagnosis from 58% to 96%, more complete identification of the molecular mechanism (42% vs. 83%), earlier molecular diagnosis (1.3 years vs. 8.6 weeks), and a rise in the relative proportion of maternal uniparental disomy from 0% to 45%. One quarter of infants was born preterm and 53% were small for gestational age. This study confirms a temporal change in diagnostic patterns, suggests a greater relative contribution of maternal uniparental disomy as a molecular mechanism, provides a more robust estimate of birth prevalence and provides evidence of in utero growth restriction for this group. These findings have important clinical and health service delivery implications and pave the way for further research in Prader-Willi syndrome.

Endocrine manifestations and management of Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a complex genetic disorder, caused by lack of expression of genes on the paternally inherited chromosome 15q11.2-q13. In infancy it is characterized by hypotonia with poor suck resulting in failure to thrive. As the child ages, other manifestations such as developmental delay, cognitive disability, and behavior problems become evident. Hypothalamic dysfunction has been implicated in many manifestations of this syndrome including hyperphagia, temperature instability, high pain threshold, sleep disordered breathing, and multiple endocrine abnormalities. These include growth hormone deficiency, central adrenal insufficiency, hypogonadism, hypothyroidism, and complications of obesity such as type 2 diabetes mellitus. This review summarizes the recent literature investigating optimal screening and treatment of endocrine abnormalities associated with PWS, and provides an update on nutrition and food-related behavioral intervention. The standard of care regarding growth hormone therapy and surveillance for potential side effects, the potential for central adrenal insufficiency, evaluation for and treatment of hypogonadism in males and females, and the prevalence and screening recommendations for hypothyroidism and diabetes are covered in detail. PWS is a genetic syndrome in which early diagnosis and careful attention to detail regarding all the potential endocrine and behavioral manifestations can lead to a significant improvement in health and developmental outcomes. Thus, the important role of the provider caring for the child with PWS cannot be overstated.

The genetics of childhood obesity and interaction with dietary macronutrients

The genes contributing to childhood obesity are categorized into three different types based on distinct genetic and phenotypic characteristics. These types of childhood obesity are represented by rare monogenic forms of syndromic or non-syndromic childhood obesity, and common polygenic childhood obesity. In some cases, genetic susceptibility to these forms of childhood obesity may result from different variations of the same gene. Although the prevalence for rare monogenic forms of childhood obesity has not increased in recent times, the prevalence of common childhood obesity has increased in the United States and developing countries throughout the world during the past few decades. A number of recent genome-wide association studies and mouse model studies have established the identification of susceptibility genes contributing to common childhood obesity. Accumulating evidence suggests that this type of childhood obesity represents a complex metabolic disease resulting from an interaction with environmental factors, including dietary macronutrients. The objective of this article is to provide a review on the origins, mechanisms, and health consequences of obesity susceptibility genes and interaction with dietary macronutrients that predispose to childhood obesity. It is proposed that increased knowledge of these obesity susceptibility genes and interaction with dietary macronutrients will provide valuable insight for individual, family, and community preventative lifestyle intervention, and eventually targeted nutritional and medicinal therapies.

A reduced-energy intake, well-balanced diet improves weight control in children with Prader-Willi syndrome

BACKGROUND

Children with Prader-Willi syndrome (PWS) have a predictable pattern of weight gain, with obesity beginning in early childhood and worsening as they get older and hyperphagia increases. Data on the most effective dietary modifications are scant and primarily anecdotal. As part of a longitudinal study investigating the natural history of PWS, we evaluated the effect of a well-balanced, energy-restricted diet on body composition and weight in young children with PWS.

METHODS

Sixty-three children, aged 2-10 years, with genetically proven PWS participated in the present study. These children had measurements of body composition by dual-energy X-ray absorptiometry and resting energy expenditure (REE), as well as a 3-day diet history analysis both before and after intervention. Energy calculations were based on the individual's REE, with the recommendation that the macronutrients of the diet consist of 30% fat, 45% carbohydrates and 25% protein, with at least 20 g of fibre per day.

RESULTS

Thirty-three families adhered to our dietary recommendations for both energy intake and macronutrient distribution. Those 33 children had lower body fat (19.8% versus 41.9%; P < 0.001) and weight management (body mass index SD score 0.3 versus 2.23; P < 0.001) than those whose parents followed the energy intake recommendations but did not alter the macronutrient composition of the diet. Those who followed our recommendations also had a lower respiratory quotient (0.84 versus 0.95; P = 0.002).

CONCLUSIONS

Our recommendation for an energy-restricted diet with a well-balanced macronutrient composition and fibre intake improves both weight and body composition in children with PWS compared to a simple energy-restricted diet.

Prader-Willi syndrome in Victoria: mortality and causes of death

AIM

The aim of this study was to describe the rates, predictors and causes of mortality in a population sample of individuals with Prader-Willi syndrome (PWS).

METHODS

One hundred sixty-three individuals with PWS (90 males and 73 females, ages: 3 weeks to 60 years) were identified from the Victorian PWS Register. Information on demographics, age at diagnosis, genetic mechanism, age at which obesity developed and last known body mass index measurement were extracted. Notification and causes of death were obtained through linkage with Australian national and state of Victoria death indexes. Survival analysis was used to estimate the probability of survival and the effect of obesity on survival. Mortality rate ratios were calculated to investigate the effect of the factors listed above on mortality.

RESULTS

Fifteen deaths were recorded (nine males and six females), corresponding to an 87% probability of survival to 35 years. The probability of survival was significantly lower for individuals with known obesity (P= 0.03), but there was no strong evidence for an effect on survival for the other factors studied. Cardiac or respiratory conditions were common causes of death after the age of 15 years.

CONCLUSIONS

The effect of known obesity on the probability of survival and the causes of death reported in this and other studies suggest an important association between obesity and early death in adults with PWS. This finding highlights the critical nature of preventative and intervention strategies aimed at minimising the effects of hyperphagia in individuals with PWS.

Bariatric surgery in hypothalamic obesity

Craniopharyngiomas (CP) are epithelial neoplasms generally found in the area of the pituitary and hypothalamus. Despite benign histology, these tumors and/or their treatment often result in significant, debilitating disorders of endocrine, neurological, behavioral, and metabolic systems. Severe obesity is observed in a high percentage of patients with CP resulting in significant comorbidities and negatively impacting quality of life. Obesity occurs as a result of hypothalamic damage and disruption of normal homeostatic mechanisms regulating energy balance. Such pathological weight gain, termed hypothalamic obesity (HyOb), is often severe and refractory to therapy. Unfortunately, neither lifestyle intervention nor pharmacotherapy has proven effective in the treatment of HyOb. Given the limited choices and poor results of these treatments, several groups have examined bariatric surgery as a treatment alternative for patients with CP-HyOb. While a large body of evidence exists supporting the use of bariatric surgery in the treatment of exogenous obesity and its comorbidities, its role in the treatment of HyOb has yet to be defined. To date, the existing literature on bariatric surgery in CP-HyOb is largely limited to case reports and series with short term follow-up. Here we review the current reports on the use of bariatric surgery in the treatment of CP-HyOb. We also compare these results to those reported for other populations of HyOb, including Prader-Willi Syndrome, Bardet-Biedl syndrome, and hypothalamic melanocortin signaling defects. While initial reports of bariatric surgery in CP-HyOb are promising, their limited scope makes it difficult to draw any substantial conclusions as to the long term safety and efficacy of bariatric surgery in CP-HyOb. There continues to be a need for more robust, controlled, prospective studies with long term follow-up in order to better define the role of bariatric surgery in the treatment of HyOb.

Runs of homozygosity identify a recessive locus 12q21.31 for human adult height

BACKGROUND

Runs of homozygosity (ROHs) have recently been proposed to have potential recessive significance for complex traits. Human adult height is a classic complex trait with heritability estimated up to 90%, and recessive loci that contribute to adult height variation have been identified.

METHODS

Using the Affymetrix 500K array set, we performed a genome-wide ROHs analysis to identify genetic loci for adult height in a discovery sample including 998 unrelated Caucasian subjects from the midwest United States. For the significant ROHs identified, we replicated these findings in a family-based sample of 8385 Caucasian subjects from the Framingham Heart Study (FHS).

RESULTS

Our results revealed one ROH, located in 12q21.31, that had a strong association with adult height variation both in the discovery (P=6.69x10(-6)) and replication samples (P=5.40x10(-5)). We further validated the presence of this ROH using the HapMap sample.

CONCLUSION

Our findings open a new avenue for identifying loci with recessive contributions to adult height variation. Further molecular and functional studies are needed to explore and clarify the potential mechanism.

Clinical management of behavioral characteristics of Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a complex neurodevelopmental disorder caused by an abnormality on the long arm of chromosome 15 (q11-q13) that results in a host of phenotypic characteristics, dominated primarily by hyperphagia and insatiable appetite. Characteristic behavioral disturbances in PWS include excessive interest in food, skin picking, difficulty with a change in routine, temper tantrums, obsessive and compulsive behaviors, and mood fluctuations. Individuals with PWS typically have intellectual disabilities (borderline to mild/moderate mental retardation) and exhibit a higher overall behavior disturbance compared to individuals with similar intellectual disability. Due to its multisystem disorder, family members, caregivers, physicians, dieticians, and speech-language pathologists all play an important role in the management and treatment of symptoms in an individual with PWS. This article reviews current research on behavior and cognition in PWS and discusses management guidelines for this disorder.

Nutritient intake of young children with Prader-Willi syndrome

BACKGROUND

Prader-Willi syndrome (PWS) is a rare genetic disorder resulting in obesity. The diets for young children with PWS must balance the importance of preventing development of obesity with the need to supply sufficient energy and essential nutrients.

OBJECTIVE

To investigate the nutritional intake for children with PWS 2, 3, and 4 years of age and compare it with Nordic Nutritional Recommendations (NNR) and intake of healthy controls.

DESIGN

Assessments of food intake for six children 2-4 years of age were performed twice a year. At the age of 2 and 3 years data was obtained by using food recall interviews and at 4 year of age a pre-coded food-diary was used.

RESULTS

The energy intake for the 2-year-old children was 3.25 MJ/day (SD 0.85) and for the 3- and 4-year olds 3.62 MJ/day (SD 0.73) and 4.07 MJ/day (SD 0.39 MJ), respectively. These intakes are 61%, 68%, and 77% of the estimated energy requirements in NNR for healthy 2-, 3- and 4-year-old children, respectively, and 60% and 66% of the energy intakes of 2- and 4-year-old children in reference populations. The children's BMI-for-age score and length growth was within the normal range during the study period. The intake of fat was about 25 E% in all age groups and reduced when compared with reference populations. In 25% of the assessments the fat intake was 20 E% or below. The intake of iron was below recommendations in all age groups both with and without supplementation. The mean intake of vitamin D and tocopherol was below recommendations when intakes were determined excluding dietary supplementations.

CONCLUSIONS

More large-scale investigations on nutritional intake are needed to further investigate dietary challenges for this patient group.